SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e978461e542c3e5fc1c1af8557d21ba494de5434d5b114d9bcedec840b00fb52' 
  AND token = 'WpcYy3gOndXsLgnvvd282Zdxq6WiP9SdJrEduymyT3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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