SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfc6cdd2a969b26cd4662f5b0cd78a56a615510c3f7afda1c01865fc9ea9d8f9' 
  AND token = 'CzT4/0RXyxNxgXI6a4L7mXDDKBeySQFqs6ER2O15sGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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