SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ec32a63daead619dbcaf0043525393592541ea350c441cfa553a715fd6ae38d' 
  AND token = '5wqf9bOPAuc1sCmTW1QtpltyHK7nFre3cTI9hUVw0gc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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