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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e46a9cd5bcfa61713df7be34f63b16a7cdc442606eb3af607ed98945969b8b48' 
  AND token = 'B1h6VK6ZYGG6LlMXGUZRolDKBbxoC0HBju2BEha1T24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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