SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16354a1dc24d1dfa79cb643db730274356fe4b749547d3e6a5eb46c5c03926f0' 
  AND token = '+I6bIwGe57DpEVEBi9yCAE0Mj6GATZ6aZJoM/WBGSWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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