SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '078856c9aa558308812190facef2fab49f7710866063ebe302b7386a27f01b64' 
  AND token = 'ciPfnd6JiImzpSVjZzlxA46FvenmmhKPk4zQmXVy+dA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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