SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aaac1afc3c714171fc9d822cfbf1e74d3233931d720f93d17c92e4c129823d7d' 
  AND token = 'SIVKNAxSDCj0JR6AXOjFzZ96lONGdDoFZjlUxRKaK3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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