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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc78e7c2a5a1676031e832a57c796468d0d4b4b1b0060dd3c373d14f372e7daf' 
  AND token = 'PL9B1ccQhoiy7qy03Nrkkwk4vbz1Mndn12hn3jwOhqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}