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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5438c35f8a5a8bbf2d4180269aad1ea6292294f287e6eb5524d9adb9e55f6ee5' 
  AND token = 'mQDDhAVJ3EK73R0Izi6DUN9OZCD7inYgAUAfWKPMA/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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