SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec6b89f7d90b2fc7a4bee880009cb51b0ec38150b15389dd3bf522e889f62c96' 
  AND token = '5QRQzvTKBTXqWEXw3W+qrVMdyPzzgBOzauL+7KW8nOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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