SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a5dec3d771065593480b943120fc16ea112ef6b66c0e9ad133d8e1641c7708b' 
  AND token = 'n/U7M71qrPLRZiFQIvCvMJ3nZ9R3BVGBgKhsrWiqwk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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