SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '940ab9118fd4d1d0507a2e69d60af9f45d5638f2670f598b54b58068f91dad82' 
  AND token = 'S9jgLcaIBA0kSehnKSt/+2ww3ivBFteQVMd1/zDDjJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}