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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5a21eac84449751b975b9c3f43480c8ced82cf325df7d7cab74f9490997e38e5' 
  AND token = 'cRWmzT/iRYBx0lguvW5XsLJsr6d+oy+cTHauUo/WMR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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