SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a52c6559488730022c179a46d37abb135bc132d1ae00ffd1eb2786992226121' 
  AND token = 'K8eEcQ6eWx2OpaF+ehy4Xr4OhxP+blvthsj+HzQcL68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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