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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '57ca1f9d4b6c671f129b02f62db2ecc6e4f642506e4055a78479211bb04c0d4c' 
  AND token = 'KwT23JDetW97x5nyRuGWueHtj/DcJMInyySUMCMxRR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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