SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3e89f344fd8f6d2d3f8d7d69d7227491b2fb1545fc234b7a59f54e49fa7bb64' 
  AND token = 'owSQRRqJ0hGPR9cY8nsTCQ7/FzoLBReeC3xoQqPKT18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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