SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a76becf7efb5a8eb09e38253ed4463e5d5868c8ff0fd286d697226732149e300' 
  AND token = 'jqx5WxlWOfk9dSJHZMRggeWMBNj5PNGKhSAmgfPkF28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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