SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3a326345bc1f208b7cc0e8445f83bad1423f66e41f46144f02ac443571873f3' 
  AND token = 't+ElaC42YGU2r4qjPYsrpX5nkGy1NTYEp95PWGbQ2vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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