SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '015cafef117e7deecc4c00006308707618fb39fd1be53d8e8790d3b116567342' 
  AND token = 'P0Lbvtq/vRlJHIQcYFraBOnq+IMtrQPqVPGod7zqNws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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