SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '836f1396fd53b96560000efbb903e2ed996e66b09852b220f92c09c926d6baef' 
  AND token = 'LtyoI2ZsaaMEn9ZVQ52gEv1jAIeuHKwDDEqOykBDzps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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