SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a396c39418a168fe519f1cbceea93189b38860d99b2bbfa483c5bc0a82fb55' 
  AND token = 'Ch1WhsmWfow5t/xxUZFd9k+soHXvGBfvF+PqQjBfylg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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