SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '168fc93cf3dd30850f8b58d22859a117dc0ffcca0aca5a3728d7441d55791b47' 
  AND token = 'bGeAolQj16oBB3/lh92grATtxS5KbYWNvfbzR7qzOhs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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