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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17ab3c561f636e7ff526c6a2f0f9c4821e92b22ef43b9095e661e11961dce87b' 
  AND token = 'UR8LttlW3dhp9GRrcUQfEf7SO+VJHhmf3WwwW+eosoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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