SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4778438d994d127943d28088aa5b42180242c1b323bf85ba0642857b1af5e14' 
  AND token = 'bFrRRuMQp85alFU/HTBADBJKfNoHKoCgjNYUzoyZGDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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