SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd46848bfbc8472d48f88f71a45381d51bd6e6687296313942a8819883cbe947' 
  AND token = 'f2mfN/qRJwZekmZtrDMP+nmWuH9fLBSbz39/CBoxdzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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