SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa6386c3580a6aa2a2e0e6597fc9bb3d80438f36c57f537bd9dfa31cf4838b6f' 
  AND token = 'qKXwC3jhID7FVzEPliZLYxBwjHTsP7NePvY1zzHBx48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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