SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd0878c1acfbcb53bf72b2cd7d868c1849d66685583f39e5a5dfed0f72a4fa29a' 
  AND token = 'g0Mx+PNCAjaLAsX/PVsscDOGZUusgo3jVSofCqWTX3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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