SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '355c6c6dadc9e5494bb8f92ca3ca08a8a2df518293dbca9b89453d7f3747f92a' 
  AND token = 'zKkQ0xeIUz3WHZU2vpOxEkWdU4yhOH4IywOR9awiJEw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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