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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d9c9e6e12fc09faba2ee62ea6ffcedebbaa1e2b2465ae484fa591a4275971ea' 
  AND token = 'QZiUBOkqCsyunaSoEWvaXfK6fMTZ19CB9/bmHGcq3bE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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