SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f8a3524234a927197529150f414e38e63e652e0cb9d1a185cf88705338f6b58' 
  AND token = 'IYpJuv6w8gAJ6yhLZTzrzlnOf5/peEbVwQerirfRYh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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