SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c3ea9554cd52e03d56b7e3baabc268c984a529dcb836f4ff63e3e055022bf17' 
  AND token = 'IQdwuWXfTwc14uQKltLdud2K5Zp0B2o6har38nOZQmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}