SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df4132e38fc979757f5a7be42d386a022dc721b9d51324a1b030022206c64160' 
  AND token = 'QAs4dlBWMEV4APBcklRk9oFrSxGLg6PwCztbYPzZ1C8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00063

JSON explain

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