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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f5889676e9ee2b0d9c58f32cadfdd87e6d96b4f24bd75818bdb5944376cfc0b8' 
  AND token = 'eLw5LCFoTt1kCKKAQlFS0K4JDGB2wxRm+SsKBzTlFsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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