SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9ea8a4d2cce38fca01048ced432b48933dc23b43b45aeaf7301f69331ce51e5' 
  AND token = 'Uq915ulVoo+5oc/avgQYwuaSFM30bJhm7JUou/d3JkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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