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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a91f26d349d157a14823b1f225871102f55abaac553d225e5273962ea81a7be7' 
  AND token = 'MnEhHSZizn89L8K8lXTQ6k4h4qDhGN3gr5cLCT/sR4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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