SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b4f8e30c91a68b8101c0ce0b6a0774b47333da59a9764fd708bce294ec6c24b' 
  AND token = 'DvnBmFMjSkdR/zwPTEY7ehl2PLUgMiJDgY96UfZ6ToU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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