SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e34209cd34180086c050b4a95426f943aaf7076af1a96bf296c96548658abbb' 
  AND token = 'WcWEr9G2JEIrCV2ho/FJwElzfvshrZSpALZXH0UgUog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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