SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17ddbbd38d9f057c35b10e75ce1857338fcf4bb4597b63be0f38819adf8439a6' 
  AND token = '4ZeUpFfeT0yxa56l5Ldl9/QP93z4AYfgdReQAeqJYy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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