SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eaf69d0976090aa35120eae1dd2ff915532575caad568633aa0920e8beba7a78' 
  AND token = '3gVcg34BoSUPco47zzJdhCfQwDBG5MKtXpU7yVoXB5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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