SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '300d7174b59080574ca062d16d4cf606173abab9befe01e06cdee6dbb708072a' 
  AND token = 'eQ8nMSSUvcHWlu7zvBd6YoboLnhpMYRh04cv+ogddFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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