SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '697ae9d476505573c6282a36292bed1b8608860f70f68652cadb74e3c5ad91de' 
  AND token = '0Cq95pnwj2Imqgd9yiJt+kn/ALGjiEHY2pEttzkX4RE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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