SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6bef70a2baf8ec6907c7490d968789340e6cc77660eea96630a5e336e8be676' 
  AND token = 'j41eDjBsN5Xw21EnkmXmc8vz8n4dlGIU847qT8OzJCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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