SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3879adb977944487bc8dcd046f698e6dea4d596c91417c477b790accca9d6bf8' 
  AND token = 'MaGX183RLqV2FUaH02lluXNAj+9+ptSYdSd1rkr8vk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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