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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7db1c6cac51e7fed527f85d8d98ad9794a3e06e68f9c45318b71a996b53b7fc7' 
  AND token = 'v0th60kF6fVk/wBiOffCgQa1VvVCD/GBwp5QVBIdX/0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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