SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ec9c55c020434c1da3cdeded33ea78cd34adb7cdca400744d1ef4c2bfb09074' 
  AND token = '7tPb9WsmnoqyHR8Sa2zgce0LdhzfFg/EIQMzvdUOODA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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