SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '823851c5c53707efe77ee0567d9abd44a865a13e8597cb22228b085498e0a931' 
  AND token = '4V9mI8ENRExewFnrKjA631naWwg0Ut3MqwppRPcgcq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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