SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29d7fb2268437c527fbbf8a0d4784303684cca53eafcdf6528fc86fe4a519a67' 
  AND token = '0nmzpXlMDZbnKh5zlTgRtNotaVAcJ1794qEWQgp2vao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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