SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2435f53ff09ece05bb2f83c1a1d2ba090d096d51e17908716a21c9bc96f63466' 
  AND token = 'MKeotPAsTYFV7zc+uO3jHFLi/gLVNqsodow+DlQBTX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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