SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '531d390280f94264cbb823300c4956273585b8872790557420b3bec05edc5f62' 
  AND token = 'iNPQuf7jwigMcTNIXu2sXF5gXf56MTfWo0KgGmYdTMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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