SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6119868143d7e7e5034a5d8e48741d4ad61245c25b23878a41bcd55bf55f5fb6' 
  AND token = 'RiuH4L7ym7VXYnaVUAQesrHToSqdUdgnWTCUr5z+azE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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