SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f91454f5982572056a75de8035acfb7c3fa74272e6d6f6df523bbfa7b2c50d2' 
  AND token = 'oP2AXgTpM5sMq4Fj0gNBCvmJxZxudDVEeg5/p4AZLb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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