SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c49a5e65cdc27f76413201b1ff344c73dc1b3a2cf9e6314626c893998a2ddd2' 
  AND token = '1unU4UVkjwTnrkhjnOIrEwczpJZulXyW5iw73H8YUs8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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