SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6d7f8a8122d1adf2a3e07d14d289b9d38b7a02986cf67510c6d21cbc2a539fcc' 
  AND token = 'lUGIiObE//WVM49ObOA1oLjkRcDDRWNNV5mpbdSchQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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