SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '604914553115c843159d477fe6b66df171436079a1ec5d9db19d2ebaed0199a7' 
  AND token = 'by7IRrrZJqvmtXjLXayCDLiY336di019ZqBcazGd9z0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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