SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6b9c96283d7f45486e2c95d379d671834ba923d1828d2f1c4612cb6f905572e' 
  AND token = 'IN0XsZLjLzuWBfbKFt16iFofLWTauE7B5fbwjX9zKQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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