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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6e11558ddd140cfda4ec9072c41bcdaf97a7bd43147594ed0657b472440fc95' 
  AND token = 'ImkHM3YscnWaiTgD1n58v+4XEanwaK5/Oo8ZnrnkO7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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