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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9a5792f07e2a28ea9cb6501ac90a16a7cefd5088753ce9332b114c58757b03d5' 
  AND token = '4NQBiHba7zcdxABFWg37Tip9An2SBWNKnAgvQ9KJkDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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