SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '749ea49f6a5f391d111998e49c20947e7b6f45d28b498822700aa4aaf4489593' 
  AND token = 'nuqWdZLWcthj7UEzyuQcXAEuH/YxQqJnKbFByxgMFuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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