SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3a76354930fa15161003aa8c7a99eb90390a272b8600dcddebc50e6273ef091' 
  AND token = '+BMyajmRTHfKbvNC9PZCIIvd1vivJ8D0MkpbSe1h8sc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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