SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7fb921deb970756dda28614ffc6f42500a66b5abedeb7e5b48b8c0c6fc87e06' 
  AND token = 'Fi+xVW2qOm2KUCel9Bp5oB/LnCBFVg5xZPzsnTevye4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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