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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '49bbc97e855c035846261a07a383e71131ebf256b2bdabba8b509eb384e90d6b' 
  AND token = 'atcMPhHy4oeQ+xZH5aZgGTzNvHuSRovZ6qOvqDBBxMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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