SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4bce0f0c23917938e823a59ddb09184274993a568fe46238c8fd47310a1b6e0' 
  AND token = '1jPLMyUvPJCdV2k8aNQApBxYeKzlE3hNGWeh+J0Ch4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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