SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5f4921e74279c8a38c43a79ddf9652307babfac87f08e19c6a65f98a8d9a943' 
  AND token = 'AQMOrkxudO3qSJoLqlylQxY3qok6D5WLZggeZUFIKYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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