SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2867359336aad3cb2034e51b8706365cec09a68fddd711c9c4b313f7fa532c91' 
  AND token = 'uGueLoz/6o1KcBtKiaXq+GLVgpxC5sjW9CzP74EiL3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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