SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37a5972be1d38971681343937588e42b1bf32d20cee9213231fa6d751e593b60' 
  AND token = 'jWUNY072HE4483r5+q1LDrbCBYrSQkMcWGaQGHBJXyU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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