SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '238a9a772b26475e02aaa1070b0b4226aa54e4b20fbd34db684c78cfc8304271' 
  AND token = '8rn/4495+KjeAfSk++4UuenbGQwDEhkFzQSJHRW8d5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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