SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89ee278aace2c998ec026c3755dc6792d62e92b16686c75896d724003523d868' 
  AND token = 'VIA7VuB0h0SSnOZ7Ihn6JCESjr1CyATHvVhEqud0gqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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