SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6219e14b50b7cc7b7c4beaeac818f0ad645db8ac4004c6082be4da78c76fb2e2' 
  AND token = 'PmyQvvEhHiw/PvBulKCjUcJBFkwJiCj3166jy87Lo9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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