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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '20cf555fd94b1a5e01ab7505f1a6bc7ca8f3db36a812bf6f60aa0e0daaa51e3c' 
  AND token = '+9MLmsw4YgSdYea/YYkPt+D2LMpdKMZRKoEAthCPUrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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