SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ef50c496aab4be514ea3279a30105af33c2a979e4fd3f21a3c4276def1299ea' 
  AND token = 'NYMIP6FIdYB1ho0SmzpHZxnZMTq7cLz5F+Runj+XcMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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