SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cb79a4a150bad78194f16e35f6e6d0826941c5eed9cf36cc819f00da1a3e5e0' 
  AND token = '5s1K23NVSxBCdXyxu5tNUOaofHuBm2wKpamnVb9F3fE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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