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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9f84414f3e7f3ea326065014a942ba3f78c6127b4d41b7c5f98adeeb5191967e' 
  AND token = 'DFRCT2/Qy9f4Du2NPz1d2xIbZcwDh1rb3YQAqRmjZmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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