SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '988927ff51c63b6ad6c544035ca415c51a17a61c5affc56387c540f40a414608' 
  AND token = 'Ot7EnBBl+VaWW6VD57AsBHEJswChpRN+P/ODyVZF9vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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