SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff7015ca4f935855df930354a2e3963df6fd9bcef293cb3c66cc82fbfc78c04e' 
  AND token = 'rBP1uEj1dBq4NvPAZ5VZuBwOWdwpcpuLjb5I+0o24Ec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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