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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7fc3b21b80feb617ccf481c4ad11f5bfccb8a9ef2c88292ffb086df0aec450a' 
  AND token = 'HWCB31tTvJB5A5EvtaNOBx2ZdLaKP3KsyezEf10Rl3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}