SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15eeba064a8869ade9d9caee688e563ba62194bceee8ab9399b5e235cc2f4b94' 
  AND token = 'pxArqJQMLRUCwi8OZTgN/+enz+NItUhb5qfaNq/0KKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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