SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcd7d4583760afd1f646563c8a7faf25d895f33f4fa70d0f0420acf09a39fddd' 
  AND token = '7rMmQlK8bJkSVPaQHkflk8kqVc7oEZgnaiU/7y+SAjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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