SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac900b4c23037d22766f8af7b313d36a4a534dbd70922025cd6ed791e7bfd080' 
  AND token = 'gkmfmLQ4KY156z+QRfMJroBmRz1kH96jBB+zVGpzWvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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