SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '796e76191f07770abd140332c610bd9226eae45ad393e50c5d4d31d8ec9d9270' 
  AND token = 'yOcPifliFw+yvtXnmgMKPZnQMMAUZS9H7rr2zUeF+Bw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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