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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcb6fc2f6c0dfec133d99dd1e8b187b7fa7edb4848e691e4bf0a1dcabd7b20df' 
  AND token = 'J6g9Tk8Q1+pZRTiLDcrJybHb3wJAwWxjsjZzZp5dzME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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