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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9a1aa6189ce07e15a6f70268869d34b3b6dbd69ac5dc3eebbceeb18a9273650f' 
  AND token = 'U3PsBDXN69iD2Y0dlHqAXcnM9WtvxxR/JfJi3GUVwEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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