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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a75ef731514641e6f0c988ae4b333c27ac8e545ca333f52a2b62d03a08f8cbad' 
  AND token = 'ekrwDryHmqIzEyEZk04UwYiory2k/1s9WPozO5JvxZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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