SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91e3bf8434dca85627ac3c09ede335e9ccc408401bebf18b0884ec91842b566a' 
  AND token = '7oox+M41oveqONAYRwcozNp5SkV69azAgndeG3UhKeA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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