SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd542691922fb74dd39656103d34c2e21c92bd36fc9d96848c9bf459d57dfc247' 
  AND token = 'CLcJ1ae9A0CRdrKHVHrTjq380P15vecxSnmoc5cBQmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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