SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c2476adde0f98e830635a64b0d3b6650bd52a8cc505a949c6931e786d290479' 
  AND token = 'iM+dxHKjvQsujEZMVjPnhpEo17YwbJAdQ/hE4XLVtSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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