SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6681b8993340d73bcaa315941d4095b53d5b47efdb809fb0a0c070da866502b1' 
  AND token = 'crlOX9TnVqLqWSZkTLLpn/NFcRmFyM7vpCHkAMlP8s4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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