SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3336d12e0bca028ad4da9f0a215164b0493a19f659800ce159208c74888353c' 
  AND token = 'rMJlBG95CPWEY3WjRMpBOZTBUKxTqjXSufYe/8I9r+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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