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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7b538249bca637858c687fe66e3125ee0dd4dba2fdcc029ca6d312e368810631' 
  AND token = 't1oATjT7QYlVqCt0k2b6FgW9mJ8YseopBy6rTX3LKHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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