SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2721f7f920c0af644d421c9f0db96b9587283fb58664b0b6b3b946c94b5f8b4' 
  AND token = 'ux8OPhgM8mJVVG+yWlOk6vY0nzutrZD6BsQXFQCZ8Uo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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