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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b8fc4452f8cecc3e7dcfd1a1a32ff8f3df58e7a24fe19d1627ef1f93316f52c4' 
  AND token = 'iUO2i5KLVzXI7sHLWB/OrRcutGRdeXexZ2J3lEqdTMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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