SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5811a404292640ff8611e4e23fff202dcf6e7c840fb0273934f3bc4ffbee897' 
  AND token = 'iCExGq60OrJLIVPsARHMXIU/ogIWcDFxefbpZ4hP640=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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