SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9a2711084d96eca14d36c45b0a9f7022ccd33ff3f689bfc353697726baac51c' 
  AND token = 'rmKIeTAlE6CPRsI8GqmbFgejw7DrHKywIESQGnGnzVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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