SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cdf892ccf14773aa7ee4fac01796de5f51796e4ebaed420854b1ad03d8e9bb1' 
  AND token = 'ZzYuXsADl5DEbceBmhZ3N+ZsUtiaSIXJCAWet1prcek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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