SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7247a954e24595c309992b4668a6e9c836db2a22b0b9b59205be3b395d49e15' 
  AND token = 'U9ADGU+dwFkbgDpn5uAr5xq7JN2fEUYuwkOAqGNofFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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