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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2db228c22e4fe6debbd9fcec2c696b32c7a482a68c70a3924b59e3fff226e4c2' 
  AND token = 'PZGGbU48f3E+4unui9W1amCogds8j17gLN4hJI7FyEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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