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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3a28cc7e98976528a494b96f983027ce51f10cd66ca590a4a8a7070ee8d8f932' 
  AND token = '6er67ZrKLivq4O/veqlXmPgz7N99JI3a26h4xyo/TrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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