SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51d693a01e863591788ffd534f5d538feadd4cb8baeb3c55eb1bce24d0ffcc66' 
  AND token = 'Wuac2wofonaVvMGHb0GgKQUA3aBBwdpH0WjgSypw5NY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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