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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f66b9db0cec3dc792affc6fee6e80a51bd2ae1dbd3aa7c9420c12ade1e87a7a5' 
  AND token = 'VjBm+SvWi8zs/Eh8Xc9Wt4bX/YaifXNIdF9CniLCGFA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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