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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27a6d93d097f54bf25766fe336b772930fd5eac4fc15f4394c243c700e1bb87a' 
  AND token = 'zPNmdOvN2lvl3os425zABWMO2usjVNuqHKtMy28pjII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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