SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc9d1fc93d0b87ef167736677e3778419b3289fa1f707cf121a7fbc988d5c468' 
  AND token = '5Vj/2cbFEzB41Fuk2JYD0ym66xLVgX7OpVgFquiGCo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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