SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a556fffcabf8dcc0457d9f220d4d8829c1b3c3e06f52f819e4f86881ba1021f' 
  AND token = 'OMO05DBxZIG0RC4LyQPnxF0h1WHg2W0K1RfV5Y6akyI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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