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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3cf9acc6e2376552aa09dc5b4e7b0e3cced6dfc6c547e3d7e6103353bc08cd84' 
  AND token = 'N5SVzfgJLpfW64BOoLBqiAhdK8B1IS1KTidp5nNUI6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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