SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5689b2f096f6a623e16f79c2f780f54d33c80cb40e33a1b3b1e8b2bec55c94ca' 
  AND token = 'grPAUVovQY5xT0jQ5YGBNm5F/Ejirp+Q8xsCoDOhK7k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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